Cayan was invited to speak about the potential impacts of global warming on California. His comments were based on a climatechange study conducted by 19 scientists from a number of universities and research institutions, i black balenciaga bag ncluding Stanford University, University of California Berkeley and Scripps.

This study is groundbreaking in that it asks, are the consequences of following markedly divergent pathways of future greenhouse gas emissions? Cayan told the committee. Using two of the latestgeneration global climate models, we compared the implications of the lowest and highest scenarios of future emissions .

Under the more optimistic scenario, technological adjustments bring changes in the way energy is produced and consumed. Still, CO2 levels in the atmosphere would be double preindustrial levels by midcentury, then they would decline to below current levels by the year 2100. The decline would require a relatively quick transformation to the use of cleaner forms of energy.

The highest scenario of emissions assumes continued intensive reliance on fossil fuels, causing heattrapping emissions to grow rapidly throughout the century. This course would result in a tripling of CO2 levels in the atmosphere, compared to the preindustrial era.

With the higher emissions, if it plays out the way the models depict things, there would be very serious consequences, Cayan said in an interview last week.

Temperatures are expected to increase under both scenarios, but the rise is much higher under the higheremission model. By midcentury, temperatures would climb 2 to 4 degrees under the loweremis black balenciaga bag sion model, 2.5 to 5.5 degrees under the higheremission model.

But the two models really begin to diverge, Cayan said, at midcentury. Toward the end of the century, average summer temperatures in the state are projected to rise about 4 to 8.5 degrees under the loweremissions scenario and 7.5 to 15 degrees under the higheremissions scenario. The temperature increases in winter under both scenarios are not as drastic, but the ratios of change are about the same.

Heat waves would be far more common, last longer and be more likely to affect coastal regions, the study concluded.

For example, the average heat wave could increase in length from about two to five days during the 1990s, to about five to 12 days by the 2050s, and six to 19 days by the 2090s, Cayan told the committee. Furth black balenciaga bag ermore, the heat wave season will likely grow considerably longer, particularly in coastal and more southern locations. In Los Angeles, for example, the heat wave season is projected to increase from about 14 weeks during the 1990s to about 19 to 25 weeks by the 2090s under the loweremissions scenario, and 31 to 37 weeks . under the highemissions scenario.

And perhaps of equal or greater concern to agriculture, industry and residents will be the impact on the Sierra, the state main source of water.

By the end of the century under the lower emissions, we would lose between 30 and 65 percent of the spring Sierra snowpack, Cayan said. Under higher emissions, we would lose between 70 and 90 percent of the spring snowpack.

Cayan said the study illustrates the importance of taking action now.

One of the messages was, because these greenhouse gases accumulate in the atmosphere over decades, the decisions and actions society makes today will have an influence, probably quite strongly, on the people making decisions in 50 years. black balenciaga bag